Climate Change Not to Blame for Extreme Winters

Previous research has suggested that climate change brings heat waves and cold snaps along with it, but a new study has come to a different conclusion.

According to scientists at ETH Zurich and the California Institute of Technology (Caltech), climate change is not to blame for our extreme winters, and in fact tends to reduce temperature variability.

In recent years, the eastern United States has experienced temperatures far below freezing, raising the question of whether or not climate change was the culprit. It has been suggested that recent warming in the Arctic relative to lower latitudes has weakened the polar jet stream. Consequently, a weaker jet stream becomes more wavy leading to greater fluctuations in temperature in mid-latitudes.

Thus, amplified Arctic warming may have contributed to the cold snaps that hit the eastern United States. However, the team from ETH Zurich and Caltech has a different theory.

"The waviness of the jet stream that makes our day-to-day weather does not change much," lead author Tapio Schneider said in a statement.

Using climate simulations and theoretical arguments, they showed that in most places, the range of temperature fluctuations will in fact decrease as the climate warms. So cold snaps will not only become more rare, but less frequent because fluctuations about the warming mean temperature also become smaller.

According to the study, published in the Journal of Climate, higher latitudes are indeed warming faster than lower ones, which means that the temperature difference between the equator and the poles is decreasing. If this difference were ever to disappear, then in theory temperature variability would no longer exist.

To test their theory, the researchers examined various climate scenarios. It showed that the temperature variability in mid-latitudes indeed decreases as the temperature difference between the poles and the equator diminishes. This goes along with climate model simulations by the Intergovernmental Panel on Climate Change (IPCC).

And while this suggests that temperature extremes will become rarer, it does not mean that there won't be any temperature extremes in the future. Other extreme events, such as storms with heavy rain or snowfall, can still become more common as the climate warms.

"Despite lower temperature variance, there will be more extreme warm periods in the future because the Earth is warming," said Schneider.

Scientists plan to study the implications these results have in further research in order to better predict how climate change may possibly affect extreme weather in the future.

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